Instrumentation and techniques of high resolution mass spectrometry are being developed and employed for studying problems of structure, biosynthesis, and drug metabolism, with special attention directed toward antibiotics Z(especially peptide, polyene and ansamycin antibiotics), biologically active marine natural products, nucleosides, alkaloids, and methylphenidate. These techniques include field desorption mass spectrometry (at high and low resolution), especially at high masses, and gas chromatography-mass spectrometry (at high and low resolution; utilizing electron impact, field ionization and chemical ionization; employing capillary as well as conventional columns). BIBLIOGRAPHIC REFERENCES: K. L. Rinehart, Jr., W. M. J. Knoll, K. Kakinuma, F. J. Antosz, I. C. Paul, A. H.-J. Wang, F. Reusser, L. H. Li, and W. C. Krueger, "Atropoisomeric Streptovaricins," J. Am. Chem. Soc., 97, 198 (1975). J. M. Liesch, J. A. McMillan, R. C. Pandey, I. C. Paul, K. L. Rinehart, Jr., and F. Reusser, "Berninamycin. I. The Structure of Berninamycinic Acid," J. Am. Chem. Soc., 98, 299 (1976).